2 Specification

3 Description

F07GEF (DPPTRS) is used to solve a real symmetric positive definite system of linear equations AX=B, the routine must be preceded by a call to F07GDF (DPPTRF) which computes the Cholesky factorization of A, using packed storage. The solution X is computed by forward and backward substitution.

If UPLO='U', A=UTU, where U is upper triangular; the solution X is computed by solving UTY=B and then UX=Y.

If UPLO='L', A=LLT, where L is lower triangular; the solution X is computed by solving LY=B and then LTX=Y.